There's more. I released a new Beta version (2.7 Beta). This Beta is supporting a bunch of new Linux Distributions :

XBMC Live 10.0 "Dharma" (with persistence)

Mint Debian 2011-01 Gnome DVD (with persistence)

CrunchBang 10 "Statler" Xfce/OpenBox (with persistence)

DouDou Linux 2010-11 (with persistence)

Obviously this beta also have a bunch of new features such as an improved management of VirtualBox update/caching/downloading, using HTTPS for stats, new crash reporter with comments and a lot of fixed bugs.

Last but not least, Portable-VirtualBox has been updated to the latest version 4.0 ! This new portable pack contains a lot of new fixes and improvements. It should be faster to start and stop. Please not that this pack will not run if you have VirtualBox 3.X or older installed on your machine. Please update it or uninstall it before.